website: fixes/changes

[houtanb]

• add the FRI logo on the explore charts
• explore chart bug fixes
  • truncated model names
  • model name overlapping baseline name (gpt-4 over public)
  • explore chart on mobile
  • gray dot in legend has hover effect (fixed in d66f198)
• smaller hero image (currently 4mb)
• fix leaderboards on phones
• add logo to lower left of footer (like on FRI site)
• make footer take up less vertical space
  • get rid of Resources column
  • change "Follow us" to just be icons and write horizontally
• Add a card about participating on ForecastBench